Controlled expansion suspended ceiling grid member

Abstract

A controlled expansion suspended ceiling grid member for suspended panel or tile ceilings comprises a web having a panel supporting flange provided along one of its marginal edges and a bead integral with the other marginal edge. The bead side walls are unconnected at the bead's base. An expansion accommodating portion is provided for accommodating thermal expansion in the beam and comprises three evenly spaced apart notches cut in the web in a manner which adapts the flange to fold downwardly away from the bead during beam expansion. The bead's top wall has slot means cut therein to essentially free the bead's side walls from transverse connection to adapt the side walls to buckle laterally out of their respective planes as the flange is folded so that the bead remains substantially horizontal and distortion along the beam's length is minimized.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A controlled expansion suspended ceiling grid beam for a suspended panel ceiling comprising a web having spaced-apart marginal edges, a flange having a panel supporting surface provided along one of said marginal edges, a bead being provided along the other of said marginal edges, said bead having substantially planar spaced-apart sidewalls which are continuous at least along the upper and lower bead portions and an interconnecting substantially planar top wall, said bead sidewalls being unconnected at the bead's base and an expansion accommodating portion for accommodating thermal expansion at a predetermined location in said beam comprising three substantially evenly spaced-apart notches cut in the web having lower and upper ends, said lower end of each notch being in the form of an apex and located at least near to the plane defined by the panel supporting surface of the flange, the web above said notches being severed in a manner to provide a web severance bridging the upper ends of said notches which leaves a first strip of the web extending along the bead's base, the bead's top wall having slot means cut therein, said slot means being substantially centrally located over the middle notch of said three notches with said slot means extending to adjacent points above the notches on each side of the middle notch, said three notches permitting said flange to bend in the area of each said notch apex whereby said flange folds downwardly away from said bead to accommodate thermal expansion in said beam, said slot means essentially freeing the bead's sidewalls as they lie in their respective planes from transverse connection over the slot means' length to adapt said side walls to buckle laterally out of their respective planes as said flange is folded, said slot means adapting said bead to collapse and maintain its longitudinal alignment without offsetting the longitudinal alignment of said flange apart from the downwardly folding flange portion. 
     
     
       2. A controlled expansion suspended ceiling grid beam of claim 1 wherein the apex of each notch lower end is near to the plane defined by the panel supporting surface of said flange so that a second strip of web extends beneath the apexes of said notches. 
     
     
       3. A controlled expansion suspended ceiling grid beam of claim 1 wherein means for weakening said first strip is provided therein below said slot means to facilitate buckling of said bead side walls and said first strip of web out of their respective planes. 
     
     
       4. A controlled expansion suspended ceiling grid beam of claim 1 wherein each of said notches is V-shaped. 
     
     
       5. A controlled expansion suspended ceiling grid beam of claim 3 wherein said means for weakening said first strip is a secondary notch cut in and extending upwardly a substantial width of said first strip. 
     
     
       6. A controlled expansion suspended ceiling grid beam of claim 1 wherein said slot means is a substantially rectangular slot which is of a significant width. 
     
     
       7. A controlled expansion suspended ceiling grid beam of claim 5 wherein said slot means ia a rectangular slot which along with said secondary notch are both substantially centrally located above said middle notch. 
     
     
       8. A controlled expansion suspended ceiling grid beam of claim 1 wherein the web above said notches is severed in a manner to remove from the web a cut-out portion the perimeter of which defines an opening bridging the upper ends of said three notches and defines a lower edge of said first strip of web. 
     
     
       9. A controlled expansion suspended ceiling grid beam of claim 8 wherein the apex of each notch lower end is near to the plane defined by the panel supporting surface of said flange so that a second strip of web extends beneath the apexes of said notches. 
     
     
       10. A controlled expansion suspended ceiling grid beam of claim 9 wherein a secondary notch is cut in said first strip which opens into said opening and extends upwardly towards the bead's base, said secondary notch weakening said first strip to facilitate buckling of said bead side walls and said first strip of web. 
     
     
       11. A controlled expansion suspended ceiling grid beam of claim 10 wherein said secondary notch extends up to the bead's base. 
     
     
       12. A controlled expansion suspended ceiling grid beam of claim 10 wherein said slot means is a rectangular slot which along with said secondary notch are both substantially centrally located above said middle notch. 
     
     
       13. A controlled expansion suspended ceiling grid beam of claim 8 wherein the distance between the apexes of the notches on each side of said middle notch is greater than the overall length of said slot means. 
     
     
       14. A controlled expansion suspended ceiling grid beam of claim 8 wherein said slot means is a substantially rectangular slot and of a width which is substantially equal to the width of the bead's top wall. 
     
     
       15. A controlled expansion suspended ceiling grid beam of claim 8 wherein said web is double walled, said bead side walls being bent towards each other at the bead's base and intregrally formed with the double walls of said web so that said side walls are unconnected at the bead's base. 
     
     
       16. A controlled expansion suspended ceiling grid beam of claim 8 wherein a single expansion accommodating portion is provided in a beam, the distance between the two outermost notches being sufficient to accommodate the expected thermal expansion in a beam when such beam is subjected to the high temperatures of a fire where beam alignment is essentially maintained during thermal expansion in the beam. 
     
     
       17. A controlled expansion suspended ceiling grid beam for a suspended panel ceiling comprising a web having spaced-apart marginal edges, a flange having a panel supporting surface provided along one of said marginal edges and a bead provided along the other marginal edge, and an expansion accommodating portion for accommodating thermal expansion at a predetermined location in said beam, said bead having substantially flat spaced-apart sidewalls which lie on opposite sides of the bead axis and which are continuous at least along the upper and lower bead portions and an interconnecting substantially flat top wall, said bead sidewalls being essentially unconnected at the bead's base, said expansion accommodating portion comprising longitudinal slot means cut in the bead's top wall for essentially disconnecting at the top the flat spaced-apart bead sidewalls along the length of the slot means and a cut-out portion in said web beneath said slot means to provide for downward folding of the flange portion beneath said cut-out portion on beam expansion, the arrangement being such that during thermal expansion in said beam as the flange portion beneath said cut-out portion folds downwardly, the spaced apart bead sidewalls by virtue of their being essentially unconnected at the top and bottom and lying on opposite sides of the bead's axis buckle laterally outwardly away from each other to control movement of the bead portions at opposite ends of the slot means to cause said bead portions to move towards each other while maintaining bead and beam alignment and hence flange alignment apart from the downwardly folding flange portion. 
     
     
       18. A controlled expansion suspended ceiling grid beam of claim 17, wherein said cut-out portion comprises three substantially, evenly spaced-apart notches cut in the web having lower and upper ends, said lower end of each notch being in the form of an apex and located at least near to the plane defined by the panel supporting surface of said flange, the web above said notches being severed in a manner to provide a web-severence bridging the uper ends of said notches which leaves a strip of web extending along the bead's base. 
     
     
       19. A controlled expansion suspended ceiling grid beam of claim 18, wherein means for weakening said strip of web is provided below said slot means to facilitate buckling of said bead sidewalls and said strip of web out of their respective planes. 
     
     
       20. A controlled expansion suspended ceiling grid beam of claim 17, wherein said slot means is rectangular in shape. 
     
     
       21. A controlled expansion suspended ceiling grid beam of claim 18, wherein the web above said notches is severed in a manner to remove from the web a cut-out portion, the perimeter of which defines an opening bridging the upper ends of said three notches and defines the lower edge of said strip of web. 
     
     
       22. A controlled expansion suspended ceiling grid beam of claim 21, wherein a secondary notch is cut in said strip of web for weakening such web to facilitate buckling of bead sidewalls. 
     
     
       23. A controlled expansion suspended ceiling grid beam of claim 17, wherein said slot means is provided in the bead top wall in a manner to remove essentially the top wall at the ends of the slot means and at a point medial of the slot means' ends so that as said bead collapses said bead sidewalls bend at the ends of the slot means and at said point medial of the slot means.